Rework message buffer

[BenediktBurger]

Reworking the message buffer to close #54

In this context, the message buffering between the normal message handler and the pipe handler is harmonized.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 94.73684% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 87.57%. Comparing base (20d57c0) to head (7850331).

Files	Patch %	Lines
pyleco/utils/pipe_handler.py	89.47%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #66 +/- ## ========================================== - Coverage 87.68% 87.57% -0.12% ========================================== Files 36 36 Lines 2867 2881 +14 Branches 347 347 ========================================== + Hits 2514 2523 +9 - Misses 293 298 +5 Partials 60 60 ``` | [Flag](https://app.codecov.io/gh/pymeasure/pyleco/pull/66/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/pymeasure/pyleco/pull/66/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure) | `87.57% <94.73%> (-0.12%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pymeasure#carryforward-flags-in-the-pull-request-comment) to find out more.

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[BenediktBurger]

This PR fixes a bug in the base_communicator: If the timeout reading for a socket message is 0, it will take the default timeout instead of not waiting at all. Only for timeout=None, the default should be taken.